Thankfully that’s literally never the case.
Kiriko was not gamebreakingly OP to the point where she was winning matches left and right, she could be killed fairly easily, and teams without her could go up against teams with her and still win.
The same will be true with Ramattra.
Also as long as the hero remains free to obtain, there’s no real ‘pay to win’ element. Pay to win is paying for an advantage that you can’t get anywhere else. If Kiriko was exclusively on the paid battle-pass, or she was a store unlock, then that would be pay to win, as you wouldn’t have access to her without paying $$ to Blizzard.